Morrisons has seen a 2.9% fall in like-for-like sales for the 13 weeks to 3 May.
The retailer closed more stores than it opened during the three-month period, which led to a net reduction in selling space of over 50,000 square feet. It is also in the process of simplifying its head office and anticipates incurring associated one-off costs of £30m-£40m during 2015/16.
However, the company says that the financial position of the group remains strong, with further good progress during the period. Net debt fell by around £150m, to £2.2bn compared to £2.3bn at the end of 2014/15.
Chief executive David Potts, who joined the company on 16 March, said: 'My initial impressions from my first seven weeks are of a business eager to listen to customers and improve. I have been very pleased by the desire and support of colleagues, and by the genuine warmth and affection for Morrisons shared by both colleagues and customers.'
He added: 'This is a business with many attributes, some unique. Our task is to use those advantages to improve the shopping trip for customers and create value.'
Looking ahead Morrisons says that it expects underlying profit before tax to be higher in the second half than the first. It is due to publish its group interim results in September.